It has been called the Sun-eating dragon, the spirit of the dead and the eye of God.

It has been a harbinger of great events, good and evil - famines, bumper harvests, wars, and the birth and death of kings.

Later today, we'll know it as the total eclipse of the Sun, when the Moon will be perfectly aligned with our star, and the lunar shadow will alight on the tip of eastern Brazil.

Racing eastwards across the Atlantic, the umbra will reach the coast of Ghana, then head across Togo, Benin, Nigeria, Niger, Chad, Libya, where the eclipse will be at its longest, lasting 4 minutes, 7 seconds, and then northwestern Egypt.

It will then zip across the Mediterranean, passing between Crete and Cyprus before making landfall in Turkey, traversing Georgia, southern Russia and then in Kazakhstan.

The shadow briefly crosses Russia again before expiring at sunset in Mongolia after a marathon of 3 hours, 12 minutes and 14,500 kilometres.

Around 2500 kilometres either side of this path of totality, observers will get a partial eclipse. For instance, about a fifth of the Sun will be obscured in the UK, southern Sweden and the southern Gulf.

Australia is among countries unable to see the eclipse. But ABC Science Online brings you photos, videos and commentary of the event as seen from Turkey.

Eclipses are infrequent events, and their rarity is enhanced by the fact that most take place over the ocean, which covers two-thirds of the world's surface, and so they go unwitnessed except by seafarers and remote islanders.

But writings dating back to the dawn of civilisation testify to thrill and dread as the Sun, the bringer of life, was gradually blotted out, the stars appeared in an indigo sky, the terrified birds stopped singing and bats left their roost.

"Nothing can be surprising any more, or impossible or miraculous, now that Zeus, father of the Olympians, has made night out of noonday, hiding the bright sunlight, and ... fear has come upon mankind," wrote the Greek poet Archilochus after an eclipse in 648 BC.

"After this, men can believe anything, expect anything.

"Don't any of you be surprised in future if land beasts change places with dolphins and go to live in their salty pastures, and get to like the sounding waves of the sea more than the land, while the dolphins prefer the mountains."

For the ancient Chinese, the eclipse was a Sun-eating dragon, which had to be scared away by the banging of cymbals and pans.

For the Vikings, it was caused by two chasing wolves, Skoll and Hati. Hindu mythology blames a demon called Rahu who spitefully takes a bite out of the Sun from time to time.

Even today, in some cultures, eclipses are believed to bring poisonous vapours and so food and water containers are turned upside-down in protection.

Watching and waiting

The most-observed solar eclipse took place in 1999, when the path of totality crossed major population centres in Europe, the Middle East and Asia.

This year, no big city lies directly on the 185 kilometre-wide path, although several, including Ankara, Lagos and Tbilisi, lie very close to it and will get a near-total eclipse.

The luckiest of all are people who inhabit the mountains of central Turkey, says NASA's veteran eclipse specialist, Dr Fred Espenak.

"A quarter million people in Sivas have the opportunity of witnessing a second total eclipse from their homes in less than seven years," he says.